DIVERS retrieved one black box yesterday and located the other from the AirAsia plane that crashed more than two weeks ago, key developments that should help investigators unravel what caused the aircraft to plummet into the Java Sea.

The flight data recorder was pulled from under a piece of wing and brought to the surface, and the cockpit voice recorder was found hours later, said Suryadi Bambang Supriyadi, coordinator for Indonesia’s national search and rescue agency.

He said the voice recorder was about 20 metres from the data recorder but remained lodged beneath heavy wreckage, and divers were struggling to free it at a depth of 32 metres.

Searchers began narrowing in on the location a day earlier after three Indonesian ships picked up intense pings from the area, but they were unable to see the devices due to strong currents and poor visibility.

The two recorders, which emit signals from their beacons, are vital to understanding what brought Flight 8501 down on 28 December, killing all 162 people on board. They should provide essential information about the plane and the conversations between the captain and co-pilot for the duration of the flight.

“There’s like 200-plus parameters they record,” said aviation safety expert John Goglia, a former US National Transportation Safety Board member. “It’s going to provide us an ocean of material.”

The flight data recorder will be taken to Jakarta, Indonesia’s capital, and the other black box will be sent as soon as it is retrieved. It could take up to two weeks to download and analyse their information, said Nurcahyo Utomo, an investigator at the National Transportation Safety Committee.

The slow-moving hunt, which has often gone days with little progress, was boosted over the weekend when the Airbus A320’s tail was lifted from the seabed. It was the first major wreckage excavated from the crash site, but the black boxes were not found inside as hoped.

Search efforts have been hampered by big waves and strong currents created by the region’s rainy season. Silt and sand, along with river runoff, have created blinding conditions for divers.

Henry Bambang Soelistyo, head of the national search and rescue agency, said on Sunday that divers had located a wing and debris from an engine. Officials have been working urgently to locate the main section of the plane’s cabin, where many of the victims are believed to be entombed.

So far, only 48 bodies have been recovered. Decomposition is making identification more difficult for desperate families waiting to bury their loved ones. Nearly all of the passengers were Indonesian.

“I still believe many victims remain trapped there, and we must find them,” said General Moeldoko, Indonesia’s military chief, who uses one name.

He said more than 80 divers are involved in the recovery effort and they have been ordered to make finding the fuselage their top priority.

The last contact the pilots had with air traffic control, less than half-way into their two-hour journey from Indonesia’s second-largest city, Surabaya, to Singapore, indicated they were entering stormy weather. They asked to climb from 32,000ft to 38,000ft to avoid threatening clouds, but were denied permission because of heavy air traffic. Four minutes later, the plane dropped off the radar. No distress signal was sent.